1. Field of the Invention
This invention relates generally to a system for the contained transfer of particulates. The invention relates more specifically to a method and apparatus for transferring hazardous particulates which facilitate the transfer without either exposure of the operating personnel and the environment to the particulate, or outside contamination of the particulate itself.
2. Description of Related Art
In the processing of particulate materials, the particulates must typically be transferred to and from processing equipment, transfer systems, and storage containers. In the pharmaceutical industry, for example, particulates are transferred from a batch processing vessel into multiple transfer containers. Typically, this is accomplished not in an automated fashion but rather through a series of manipulative steps performed by plant operators. A transfer container such as a bag is placed on the discharge port of a piece of equipment, the port is opened to fill the bag, the port is closed, the bag is removed, and the top of the bag is secured.
In the processing and material transfer of hazardous particulates, however, such as highly potent pharmaceuticals, the particulates must be transferred without exposure of the operating personnel to the health hazards associated with the pharmaceuticals. In concentrated form, these pure drugs and/or their intermediates pose a serious health hazard. Exposure to as little as parts per million levels of the drugs can result in chronic health problems and even death. Heretofore, the material transfer was accomplished by personnel wearing personal protective equipment, i.e., full-body protective suits and respirators. Such protective equipment, however, is cumbersome, hot, and uncomfortable to wear; requires operator time to don and doff; and must be washed and incinerated after use.
Additionally, for two reasons, it is desirable that the transfer of such particulate materials be accomplished in a contained manner. First, it is often necessary to protect the particulates themselves from environmental contamination. Second, the particulates being transferred in applications such as the processing of pharmaceuticals are often in a very concentrated state, and the accumulated loss during a series of transfer steps can have a substantial negative impact on the economics of the process.
The means for securing the top of filled transfer containers such as plastic bags has conventionally consisted of twisting the material of the bag lengthwise and tying it off with a wire or plastic closure. While a means for securing the bags by a method such as heat sealing would be more reliable, faster, and convenient, the processing environment has heretofore precluded the use of a conventional heat seal machine. Because of the presence of both flammable gases and combustible dusts resulting from uncontained particulates, the potential for explosion resulting from arcs, sparks, and high temperature exposed surfaces has rendered the use of heat sealing impossible.
In order to provide for the contained transfer of particulates, one conventional process employs a continuous tube of flexible material that is packed onto the discharge port of a vessel. The bottom of the tube is secured by twisting and tying, and the first of a series of bags is filled. The material above the filled bag is then twisted, a lower and an upper tie are applied, and the filled bag is detached by cutting the twisted material between the ties. The material above the upper tie then forms the bottom of the next bag to be filled. While this method provides for some containment of material, a significant potential for exposure arises during the step of cutting the twisted material between the ties. Additionally, an exposure problem arises when the supply of tube is depleted. That is, when it is necessary to remove the top of a tube from the discharge port, the presence of particulate on the tube and the port necessitates that the operators don protective gear. Furthermore, this method fails to address the mechanics of discharging the contents of the filled bag into a vessel in a subsequent processing step.
Furthermore, particulates such as those employed in the pharmaceutical industry are often used in conjunction with solvents and tend to agglomerate within a vessel. In view of the aforementioned value associated with the particulates, however, it is highly desirable to discharge the entire contents of a vessel. Conventionally, if the contents of a vessel were not discharging properly, the vessel would be opened and operators in protective gear would either rod the vessel or enter the vessel to facilitate the discharge. Either method, however, not only interrupts the process but can pose a danger to the safety of the operators and contaminate the product.
Finally, certain conventional technologies employ stainless steel vessels equipped with hermetically sealed ports for the transfer and storage of pharmaceutical products. Such containers, however, along with all of their associated hardware, are expensive to fabricate. Even more importantly, they must be thoroughly cleaned to remove all traces of the particulate prior to reuse in order to avoid quality issues such as cross-contamination. The cleaning and certification program, however, is expensive and not entirely reliable, as it is extremely difficult to remove all traces of particulate from the container.
As an alternative to stainless steel vessels, at least one conventional technology has employed the continuous tube of flexible material described above. While such a transfer container may be disposable, it must also satisfy the rigorous physical requirements imposed by the pharmaceutical industry. That is, the container must possess the required physical characteristics for the particulate transfer service, namely, antistatic properties, flexibility, and high strength. Conventional containers, however, while exhibiting some combination of some of the desired characteristics, have never possessed all of the properties required for use in a system such as that of the present invention.
It is an object of the present invention to provide an economical and reliable system for transferring particulates which facilitates the transfer without either exposure of the operating personnel and the environment to the particulate, or environmental contamination of the particulate itself. It is a further object of the present invention to provide a method and apparatus for contained transfer that employ a series of transfer containers. It is an even further object of the present invention to provide an apparatus that is capable of performing a repeatable high temperature material heat seal of a flexible transfer container. It is a still further object of the present invention to provide an apparatus for the contained mechanical breakup of agglomerated particulates in a piece of processing equipment. Finally, it is a still further object of the present invention to provide a transfer container material which possesses the combination of antistatic and mechanical properties required for use in the contained transfer system.
Accordingly, the present invention advantageously relates to a multiple o-ring canister assembly which can be attached to either the discharging port or charging port of a piece of processing equipment. The canister has a series of circumferential o-ring grooves which allows the attachment of a series of individual transfer containers. In a charging mode, for example, once the particulate is charged to the processing equipment, a first transfer container is collapsed and a second transfer container is placed in the next o-ring groove, thereby containing the remaining contaminated section of the first transfer container. The first transfer container is removed through a bag-out sleeve which is an integral part of the second transfer container. The process is repeated in a stepwise fashion by moving to the next groove in the canister until the process equipment is completely charged.
In a second embodiment, the invention relates to a continuous sleeve cartridge assembly which holds a continuous series of transfer containers initially joined top to bottom in a long, sleeve-like manner. After a first transfer container is filled, an area between the first transfer container and a second transfer container is heat sealed closed and the middle of the heat seal is cut to separate the first transfer container from the second. The heat seal forms the top of the first transfer container and the bottom of the second transfer container.
The invention further relates to an apparatus that is capable of performing a repeatable high temperature material heat seal to secure the transfer containers. The invention facilitates the use of heat sealing technology in environments that are classified as hazardous. The device utilizes all necessary precautions to prevent the presence of arcs, sparks, and high temperature exposed surfaces so as to prevent an explosion as a result of the flammable gases and combustible dusts that may be found in such environments. In addition, the apparatus utilizes a dual temperature feedback system to ensure that a complete seal has been produced.
The invention further relates to a rodding apparatus that facilitates the discharge of particulates which may have agglomerated in a piece of processing equipment, such as particulates which have bridged over a discharge valve. The rodding system is installed in the top of the processing equipment, thereby allowing the rodding to be conducted in a contained manner. The device comprises a closure plate which has an integral long rod and blade assembly. Movement of the rod in the x, y, and z axes is accomplished by the use of a long bellows assembly. The closure plate comprises two glass view ports for use with a video camera and light source to facilitate the rodding process.
Finally, the invention further relates to a flexible, thermoplastic, disposable transfer container material which comprises a base resin, an antistatic agent, and a filler. The material not only possesses the necessary combination of antistatic and mechanical properties for use in the contained transfer system, but can be fabricated in various formulations and/or configurations to meet the needs of a specific application.
The advantages associated with the present system are numerous. First, from an exposure standpoint, the invention provides for a xe2x80x9cshirt-sleevexe2x80x9d environment in which the full-body protective suits and respirators associated with the conventional methods are unnecessary during discharging and charging operations. Additionally, operator dexterity is enhanced in the shirt-sleeve environment. Second, from a containment standpoint, the invention provides for improved economics resulting from the enhanced recovery of particulates. An even greater economic benefit, however, is that the invention facilitates the processing of high potency compounds in an uncontained processing facility. By providing for continuous containment even when it is necessary to mount subsequent transfer containers, the invention overcomes the prior art problem associated with the presence of particulate on both the tube and the vessel port. Also, the present system solves the mechanics of discharging the contents of a filled bag into a vessel in a subsequent processing step.
Additionally, the improved containment contributes to the possibility of employing heat sealing in an environment which heretofore has contained an unacceptable level of combustible dusts. The rodding apparatus facilitates the contained mechanical breakup of agglomerated particulates while eliminating the risk to operators. Finally, the flexible transfer container itself possesses the necessary combination of properties for use in the present system, while providing a reliable, low cost, and disposable alternative to the conventional stainless steel containers.